Just saw this thread, and I second Chris' observations: at scale we are
seeing huge gains in jobstart performance with PMI2 over PMI1. We
*CANNOT*loose this functionality. For competitive reasons, I cannot
provide exact
numbers, but let's say the difference is in the ballpark of a full
order-of-magnitude on 20K ranks versus PMI1. PMI1 is completely
unacceptable/unusable at scale. Certainly PMI2 still has scaling issues,
but there is no contest between PMI1 and PMI2. We (MLNX) are actively
working to resolve some of the scalability issues in PMI2.